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5.2 Calculating SRL Minimum Required Fall Clearance (MRFC)
5.2.1 Overhead Anchorage Application
The DuraTech SRL-R in an overhead condition has six metrics, labeled A – F, measured from the walking/working surface.
A = SRD Deceleration Distance
B = D-Ring Shift and Harness Stretch
C = Safety Factor
D = Sub Total- Minimum Required Fall Clearance
E = *Additional Fall Clearance Calculation Due To Swing Fall
F = Total Required Fall Clearance
The MRFC for an overhead anchorage, with no swing fall condition, is calculated as A+B+C=D. The user must be aware that if a
swing fall hazard exists, as shown in Figure 5, additional steps are required. Use Chart 1 on the following page to determine the
amount of swing fall, and place that value in E. Add the E value to the D value to determine the total MRFC.
Figure 4 - Calculating Required Fall Clearance: Overhead Anchorage
Deceleration Distance
Maximum allowable length of cable or web that may payout from the SRD once
A
2 1/2 ft
deceleration of the user has begun and after a fall event occurs. For work in low
clearance areas, see Table 1B for Typical Performance
Dorsal D-Ring Shift and FBH Stretch
B
1 ft
Combined amount of Dorsal D-ring up-shift and harness webbing elongation during
entire fall event
Safety Factor
C
11/2 ft
Added length to account for other factors such as an improperly adjusted harness,
actual worker height or worker weight
Sub Total- Minimum Required Fall Clearance
D
5 ft
for direct overhead use of SRD with No Swing Fall; sum of A, B and C only
*Additional Fall Clearance Calculation
E
____ ft
due to Swing Fall (using Chart 1)
Total Required Fall Clearance
F
____ ft
Including sub-total D and Swing Fall E (from Chart 1)
1. Overhead Anchorage 2. Walking/Working Surface
MCS03 Rev B
Figure 3 - Overhead Anchorage
3. Nearest Lower Level or Obstruction
A Overhead Anchorage
B DuraTech 3-Way
C Line Constituent
D SRD Connection to FBH
E
Walking/Working Surface
A
Anchorage
B
Self-Retracting Lifeline
C
Walking/Working Surface
D
Swing Fall Impact after fall event
E
Next Lower Level or Obstruction
050120
Figure 5 - Swing Fall Hazards: Overhead
7
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